A typical power generator, which is an example of rotary electric machines, induces three-phase AC power in three-phase stator windings, and rectifies the three-phase AC power to generate DC power. Then, the typical power generator supplies the generated DC power to a battery via electrical lines connected between output terminals thereof and the battery. The typical power generator also supplies the generated DC power to electrical loads as their operating power.
While such a power generator is operating to supply generated power to a battery and/or electrical loads from the output terminal thereof via the electrical lines, disconnection of the electrical lines from the battery or the output terminal of the power generator causes a high voltage (a high pulse) across a corresponding phase stator winding due to the excited state of the corresponding phase stator winding. This disconnection will be referred to as load dump, and the high voltage generated due to load dump will be referred to as a load-dump surge.
Such a load-dump surge would reduce the reliability of the power generator itself and/or the electrical loads. Thus, there is a requirement to protect the power generator itself and/or the electrical loads from such a load-dump surge. Japanese Patent Application Publication No 2012-16158 discloses an example of technologies to protect a, power generator itself and/or electrical loads connected thereto from such a load-dump surge.